This invention provides a budesonide/formoterol dry powder inhaler comprising: a reservoir containing a dry powder medicament and an arrangement for delivering a metered dose of the medicament from the reservoir; a delivery passageway for directing an inhalation-induced air flow through a mouthpiece, the delivery passageway extending to the metered dose of medicament, wherein the medicament comprises micronised formoterol fumarate, micronised budesonide and a lactose carrier, the lactose carrier having a particle size distribution of d10 = 20-65 µm, d50 = 80-120 µm, d90 = 130-180 µm and <;10 µm = <;10%.